1. A type of variable star that periodically brightens and dims in a regular, predictable pattern, used by astronomers to measure distances in space.
Usage: astronomy; often capitalized as Cepheid variable

Examples

• Astronomers use cepheids as cosmic distance markers because their brightness variations are consistent and measurable.
• The discovery of cepheids in other galaxies proved that the universe extends far beyond the Milky Way.
• A cepheid's period of pulsation is directly related to its intrinsic brightness, a relationship known as the period-luminosity relation.
• Edwin Hubble observed cepheids in the Andromeda Galaxy to determine its distance from Earth.
• The brightness of a cepheid can change by up to a full magnitude over the course of days or weeks.